In general the term electromagnetism deals with the mutual interaction of electrical charges. When the charges are stationary, we have problems on electrostatic fields and forces. If the charges are moving uniformly so that a steady current is produced, then we have problems on magnetic fields and forces (see chapter 3). Lastly, if the charges are accelerating, so that the current produced is time varying, then electromagnetic wave theory is involved, from which radiating energy ideas may develop.
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